I would recommend leadTec. Professional, helpful and trustworthy.
http://www.leadtecservices.com/index.html I wanted a professional company to help get my certifications done fast, correctly and without "run-around " and they fit the bill. I am also a certified lead paint visual inspector, myself but I don't do inspections.
Nevertheless, If you have a rental property and are doing this inspection to comply with Marylnd law, I can give you some tips:
1. Make sure that your exterior painted surfaces are in good condition. You may have to have exterior surfaces cleaned, primed and repainted if they are chipping, flaking etc. If you have outdoor surfaces that do not need paint, but have chips of paint, you should just remove the leftover paint so that the surface is "unpainted." It's a good idea to do this before you call the inspector.
2. Make sure your interior paint is in good condition. If you have areas of damaged paint in the hallways etc., you may want to strip them and refinish them or have them painted by a professional. If you do it yourself. Remember to remove damage, clean the area, prime, and then use 2 coats of paint ... so that the job will last. It's also a good idea to do this before you call the inspector.
3. If you have original wood windows, make sure they are in good condition. Old windows are okay, but if you have tenants they should be able to clean out the window well. So, you can keep your old windows, but make sure they glide smoothly. Then clean out your window wells. Then make sure that if the wells have old chipped paint or old splintery wood that you remove loose paint, sand and prime and paint with good quality paint so the area is smooth and cleanable. If yours are in bad shape, you may need to cap the window wells with aluminum sheeting or vinyl. The point is to get a surface in there that someone can keep clean.
4. If you are having an inspection done to comply with the MDE lead paint regulations, you should also clean the place thoroughly. The inspectors will take one sample from the floor or windowsill and one sample from the window well in a room that has original wooden widows. So clean accordingly and keep the areas clean before your inspection. I used murphy's oil soap and mopped the wooden floors a couple of times and finally with a fresh mop (sponge mop) and water. I cleaned the window wells and sills with murphy's oil soap and simple green before and after painting or capping them. After getting up the dirt, I removed any soap/dirt residue with clean rags using fresh water.
5. After cleaning prevent contamination by taking off shoes when re-entering the room. Lead is everywhere, and outside dirt can bring lead residue into the rooms. Leadtec should also let you know if there are any problems on your first consultation. What you want to avoid is having to RE-test for dust.
6. You can also ask them if you can qualify for just a VISUAL inspection instead of a dust sample test.
7. Finally, if your inspection is for rental purposes, make sure you tell your tenants how to keep the place clean in compliance with the recommendations for lead-dust safety. They should vacuum, dust and mop occasionally and clean out the window wells of dirt occasionally. You also need to disclose that your house may contain lead paint etc according to MD law... If they have kids, let them know that they should also make sure the child has proper nutrition and vitamin supplements if needed.
If you are looking for an inspection for your own home, I would also recommend LeadTec. They have advanced equiptment and can do all kinds of diagnosis if you want to make sure your new house is lead-safe before and after a renovation.
Good Luck!